Latching assembly for a rotary electromagnetic device



1966 J. J. BIEGER ETAL.

LATCHING ASSEMBLY FOR A ROTARY ELECTROMAGNETIC DEVICE 2 Sheets-Sheet 1 Filed Aug. 6, 1964 INVENTORS Nov. 29, was J. J. BIEGER ETAL. 3,289,133

LATGHING ASSEMBLY FOR A ROTARY ELECTROMAGNETIC DEVICE Filed Aug. 6, 1964 2 Sheets-Sheet 2 a 4? g 25 54 I 44 L ATTORNEYS United States Patent 3,289,133 LATCHING ASSEMBLY FOR A ROTARY ELECTROMAGNETIC DEVICE Jacob J. Bieger. Queens, and Alois Stanher, Great Neck,

N.Y., and William Henninger, Paramus, N.-I., assignors to Daco Instrument Company, Brooklyn, N.Y., a corporation of New York Filed Aug. 6, 1964. Ser. No. 387,895 11 Claims. (Cl. 335-253) This invention relates to rotary electromagnetic indicators or actuators, and, in particular, to an attachment for latching or holding the armature of such a device in its energized position.

The present invention has particular utility with rotary electromagnetic indicators including a coil and armature, wherein rotation of the armature manifests the application of an electrical signal to the coil. In such devices it is frequently necessary that a visual indication be maintained until the indicator is manually reset, even though the actuating signal has disappeared. Since the indicator normally includes a return spring or the like, it is necessary to provide an additional force to overcome the return bias of the spring and latch the armature in its energized position. In the prior art, this latching force has been provided by the indicator mechanism itself. However, the known arrangements have not yielded satisfactory results in the case of miniature indicators which must operate on extremely low power inputs where additional power for operation of the latching mechanism is not available.

It is therefore the main object of the present invention to provide a latching mechanism for a rotary electromagnetic indicator which does not require energy from the operating signal applied to the indicator.

Another object of this invention is to provide a latching mechanism having increased holding power.

Another object of the invention is to provide a manually releasable armature latching mechanism, which, upon release, exerts an additional return force on the armature.

Still another object of the invention is to provide a more compact latching mechanism for a rotary indicator.

Briefly, the invention includes a separate latching rotor which rotates with the armature of the electromagnetic device, and cooperates with a holding means movable along the armature axis of rotation. The holding means may be magnetic or mechanical or both, and is adapted to hold the latching rotor when the armature is rotate-d to a predetermined position. To release the armature, the holding means is moved axially away from the latching rotor whereby the armature is permitted to return to its initial position.

The manner in which the above and other objects of the invention are accomplished will be explained in greater detail below with reference to the attached drawings, wherein:

FIG. 1 is an exploded view of a rotary electromagnetic actuator with a combination mechanical and magnetic latch according to the invention;

FIG. 2 is a side sectional view of the actuator and latching mechanism;

FIG. la is a perspective view of a specific latching rotor;

FIG. 3 is a top view of the actuator and latching mechanism;

3,289,133 Patented Nov. 29, 1966 lCC FIG. 4 is a sectional view along the line 4-4 of FIG. 2; 7

FIG. 5 is a sectional view along the line 5-5 of FIG. 3;

FIG. 6 is a sectional view along the line 6-6 of FIG. 3; and

FIG. 7 is a top view showing the color disc and window by means of which the armature displacement is observed.

In the following specification the preferred embodiment of the invention is described as including a combination mechanical and magnetic latching mechanism. However, it will be obvious to those skilled in the art that either type of latching mechanism may be used alone to hold the armature of the electromagnetic actuator in its energized position.

The invention will be described for use with a particular indicator, but the latching mechanism of the invention does not require a specific indicator or actuator, and would have utility with various types of rotary armatures having suitable projections with which the invention could be employed.

In the preferred embodiment, the indicator is the same as that described in US. application No. 223,164 of Bieger now Patent No. 3,234,436, filed September 12, 1963, and assigned to the assignee of this invention. The indicator includes a cylindrical stator 10 having integral outer pole pieces 12 and 14, and a hollow central pole piece 16. A rotor shaft 18 is journalled in bearings 20 and 22 within central pole piece 16, and a bowshaped armature 24 is secured to shaft 18 immediately above the free end of pole piece 16. A portion 18 of shaft 18 extends exteriorly from the closed end of stator 16 for cooperation with the latching mechanism of the invention as explained more fully below.

The conventional coil assembly of the electromagnetic device, indicated generally at 26, is received within stator 10. Coil assembly 26 is capable of creating a magnetic field in the stator which will pull the armature 24 into alignment with outer pole pieces 12 and 14 as described more fully in application No. 223,164.

A coiled, flat return spring 28 is secured to both the armature and stator assemblies, and serves to return armature 24 to its initial position when the coil energizing source is removed. A color disc 30 is fixed to the exterior surface of armature 24, whereby the angular displacement of the armature can be observed by noting the movement of disc 30 through a window 32. Disc 30 may include projections 31 and 33 which abut against stator poles 12 and 14 to limit rotation of armature 24. The entire indicator assembly above described is contained within a cylindrical housing 34 made of a nonmagnetic material.

According to the invention, a latching rotor 40 is fixed to the exterior portion 18 of armature shaft 18 and adapted to cooperate with a latching attachment to hold the a-nrnature in its energized position. Latching rotor 40 is made of a magnetic material and includes opposing blades 42 and 44 integrally formed with a central hub 46. Hub 46 may be fixed t-o armature shaft extension 18' in any desired may so that latching rotor 40 rotates with armature 24 when coil assembly 26 is energized.

The latching mechanism is supported in a U-shaped yoke 48 comprising parallel arms 49 and 51 having respective openings '56 and 52 through which housing 34 is inserted. The indicator is fixed to the yoke 48 so that 3 no relative movement is possible between the two along the actuator axis.

A non-magnetic movable bracket 54 is mounted in a canted notch 56 in the end of the yoke arm 49. Bracket 54 includes long and short parallel arms 53 and 69, respectively, with long arm 58 adapted to slide within notch 56.

A push rod 61 is slidably received in aligned apertures 62 and 64 of the yoke 48, with one end 66 of the rod peened to the transverse bar of bracket 54. Push rod 61 includes an enlarged head 63 for manually moving the rod in apertures 62 and 64. A C-shaped lock Washer 68 is pressed into a circular notch 70 on rod 61 between parallel arms 49 and 51 of yoke 48. An annular washer 72 is placed adjacent lock washer 68 and a coil spring 74, enveloping rod 61, compressed between Washer 68 and the portion of yoke arm 49 surrounding aperture 62. Looking at FIGURE 1, rod 61 is thus biased to the right a distance limited by abutment of lock washer 68 against the inner surface of yoke arm 51.

A pair of small rectangular permanent magnets 76 and 78, oppositely poled as illustrated, are cemented to the interior of bracket 54 adjacent the inner surface of short bracket arm 60. The magnets are separated by a non-magnetic spacer 80 and the outer end magnetically closed by a small bar 82 made of a magnetic material. The inner ends of magnets 76 and 78 extend tangentially into the path of rotation of latching rotor 40, whereby, when armature 24 and latching rotor 41} rotate, blade 44 contacts these inner ends to close the flux path between the magnets. The attraction force of the magnets is greater than the return force of spring 28 so that the entire rotary mechanism is held in its energized position after the energizing signal is removed from coil 26.

To release the latch, :push rod 61 is moved to the left by manually depressing head 63. When the latching magnets 76 and 78 are thereby moved a sufiicient distance beyond latching rotor 41), the holding force is removed and spring 28 returns the entire armature assembly to its initial position. When the manual force is removed, coil spring 74 returns the push rod 61 to its illustrated position.

For increased holding power, the device may readily incorporate a supplemental mechanical latch. For this purpose, the short bracket arm 60 includes a circular opening 1% through which a round axle pin 102 passes. A pawl 104 is secured to axle pin 1112 exterior of the mounting bracket with a Washer 196 and an annular collar 1118 exterior of the pawl. A coil spring 110 is placed around collar 108 with one end 112 hooked over pawl 104 and the other end 114 anchored in a small hole 116 in short bracket arm 60. A C-shaped lock washer 117 is force fit into a notch 118 in axle pin 102 to hold the assembly together. Pawl 104 includes an angled surface v119 which terminates in a retaining notch 120. A projection 122 assists in holding the hooked portion 112 of spring 110.

When coil 26 is energized, causing latching rotor 40 to rotate, the upper edge 124 of rotor blade 44, which may be bevelled as shown, moves toward angled surface 119 of pawl 104. Continued movement of the latching rotor causes pawl 104 to rotate clockwise on axle 102 until the edge .124 has passed over the entire angled surface 119. At this point, spring 110 forces pawl 104 in a counter-clockwise direction so that the latching rotor 40 rests in pawl notch 120. When the energizing signal is removed, notch 120 prevents indicator spring 28 from returning the armature to its initial position.

To unlatch the armature, push rod 61 is manually depressed, moving pawl 104 in the direction of arrow 125 and releasing latching rot-or 40, whereby the armature is rotated back to its start position by spring 28.

The embodiment of the latching rotor illustrated in FIGURE 1a is particularly useful in cases wherein the mechanism is subjected to severe environmental vibration or shock conditions. In this case the latching rotor consists of a pair of permanent magnets and 92 arranged side-by-side with opposite poles adjacent each other. The magnets are separated by a nonmagnetic spacer 94, and one pair of ends closed by a magnetic keeper bar 96. The structure is basically the same as that of the latching magnets 76 and 78, however, the respective magnets are arranged so that upon energization of the coil, the south pole of rotor magnet 90 contacts the north pole of latching magnet 76, and the north pole of rotor magnet 92 contacts the south pole of latching magnet 78. The attraction of the unlike magnetic poles increases considerably the holding force exerted on the armature, thus diminishing the the possibility of accidental release due to environmental shocks or the like.

This embodiment has the further advantage of increasing the return speed of the armature when the latch is released. This is because depression of push rod 61 moves the south pole of magnet 78 adjacent the south pole of magnet 94, whereby the mutual repulsion of like magetic fields exerts an additional return force on the armature. A further advantage of this embodiment is a saving in space, since the push rod need only be moved a distance sufiicient to bring the like magnetic poles together. This saving is a material consideration in the case of sub-miniature indicators.

Although preferred embodiments of the invention have been illustrated and described, the invention is not so limited and many modifications thereof will be obvious to those skilled in the art. For example, the principles of the invention could be utilized to latch an armature in any one of a plurality of positions. Accordingly, the invention should not be limited except as defined in the following claims.

What is claimed is:

1. A latching device for use with a rotary device having an armature rotatable to a predetermined position, comprising a latching rotor connected from said armature, a support yoke secured to said rotary device, a movable bracket mounted on said yoke for movement in the direction of the rotational axis of said armature, and means mounted in said bracket for holding the latching rotor when said armature is rotated to said predetermined position, said means releasing said latching rotor when said bracket is moved a predetermined distance in said direction. 7

2. A latching device according to claim 1, wherein said latching rotor is made of a magnetic material and said holding means comprises permanent magnet means.

3. A latching device according to claim 2, wherein said latching rotor comprises permanent magnet means.

4. A latching device according to claim 2, wherein said permanent magnet means comprise at least two permanent magnets arranged side-by-side with opposite poles adjacent each other, whereby movement of the armature to said predetermined position causes said rotor to close the magnetic circuit of said permanent magnets.

5. A latching device according to claim 4, wherein said latching rotor comprises at least two additional permanent magnets arranged side-by-side with opposite poles adjacent each other.

6. A latching device according to claim 1, wherein said holding means include a spring biased pawl including a retainer portion for holding said latching rotor.

7. A latching device according to claim 2, wherein said holding means includes a spring biased pawl including a retainer portion for holding said latching rotor.

8. For use with a rotary electromagnetic device including a fixed stator, an armature, and an elongated shaft secured to said armature and rotatable therewith to a predetermined position, said shaft extending exteriorly of said stator, latching means comprising a latching rotor secured to said shaft exterior of said stator, a yoke secured to said device, a rod slidable in said yoke in a direction parallel to said shaft, a bracket secured to said rod, spring means biasing said bracket and rod to a given position, and means mounted in said bracket for holding said latching rotor when said armature is rotated to said predetermined position, said means releasing said latching rotor when said rod is moved a predetermined distance in said direction.

9. A latching device according to claim 8, wherein said latching rotor is made of a magnetic material and said holding means comprises permanent magnet means.

10. A latching device according to claim 9, wherein said latching rotor comprises permanent magnet means.

11. A latching device according to claim 9, wherein said permanent magnet means comprise at least two permanent magnets arranged side-by-side with opposite poles adjacent each other, whereby movement of the armature to said predetermined position causes said rotor to close the magnetic circuit of said permanent magnets.

No references cited.

BERNARD A. GILHEANY, Primary Examiner.

GEORGE HARRIS, IR., Assistant Examiner. 

1. A LATCHING DEVICE FOR USE WITH A ROTARY DEVICE HAVING AN ARMATURE ROTATABLE TO A PREDETERMINED POSITION, COMPRISING A LATCHING ROTOR CONNECTED FROM SAID ARMATURE, A SUPPORT YOKE SECURED TO SAID ROTARY DEVICE, A MOVABLE BRACKET MOUNTED ON SAID YOKE FOR MOVEMENT IN THE DIRECTION OF THE ROTATIONAL AXIS OF SAID ARMATURE, AND MEANS MOUNTED IN SAID BRACKET FOR HOLDING THE LATCHING ROTOR WHEN SAID ARMATURE IS ROTATED TO SAID PREDETERMINED POSITION, SAID MEANS RELEASING SAID LATCHING ROTOR WHEN SAID BRACKET IS MOVED A PREDETERMINED DISTANCE IN SAID DIRECTION. 